Yey: run your marathon before 40! I definitely can recommend Berlin. I ran 9 of them (also New York, f.i.) and Berlin wins all of them! Well organized (of course), unexpectedly warm cheering, not difficult (flat), nice views. And I have to repeat: it is really well organized ;) Fingers crossed that it works out!
Thanks for your feedback, that's really helpful. New York was top of my list, but I heard it's difficult to enter as a foreigner and it's expensive (entry fee, hotel, flights) this is why I'm not considering anything too far. Do you have a training schedule or any advice?
I had a training schedule for Berlin very similar to the one presented in this document. I am not all that ambitious regarding time and my goal was 4 hours 15 minutes. This is also how I actually finished "the Berlin". Check other schedules (in this same document), that will help you run faster if this is to your liking. My advice is also: schedule is just a frame... listen to your body. And: the essential part of preparation is the "rest enough" part. Fingers crossed! And I am happy to further talk about anything you think I might help you with.